Governmental agencies administer requirements with respect to the lighting requirements of an aircraft. For example, the U.S. Federal Aviation Administration (“FAA”) requires certain minimum lighting requirements including locations of lights, color, and visibility (corresponding to light output).
Light-emitting diodes (“LEDs”) are advantageously used to provide lighting because LEDs are energy efficient relative to previous technologies, and because, as solid-state devices, LEDs have long lifetimes compared with other technologies. LED light fixtures have become common in aviation lighting applications, such as navigation lights, beacons, landing lights, etc. However, over the long lifespan of a typical LED, its light output will degrade in an manner that is difficult or impossible to predict, rather than simply “burning out”—as was the case with previous, incandescent bulb and flashtube lights.
Due to this unpredictable degradation, aircraft lighting manufacturers have had difficulty providing a way to determine when a light fixture no longer meets the FAA specifications and needs replacement (the “end of life” or “EOL” of the fixture). One approach used in the industry for determining light fixture replacement is to designate a fixed end of life based upon a predetermined number of operating hours. However, if the light output of the fixture has dropped significantly below the specified value before the predetermine number of hours, then the fixture may be operating past its end of life. Conversely, if the light output is still significantly above the specified value at the predetermined number of hours, then the end of life determination may be premature.
Several other known methods use software approaches to make this determination. However, the use of software complicates aircraft-related certification.
There is a need for a way to more effectively determine when an aircraft light fixture is non-compliant with the FAA and other requirements.